Braiding machines have long been used in industry, for example, to braid metallic wire into electrical or electronic cable as a protective armor or into hydraulic hose and cordage as a load bearing structure or into rope, either metallic or non-metallic.
The two main kinds of braiding machines presently used are maypole-type braiding machines and internal cam rotary-type braiding machines. The maypole-type machine uses a plurality of spool carriers to carry filament bobbins in serpentine-like paths about a track plate. The track plate consists of two separate paths: each path 180 degrees out of phase from the other. One path moves clockwise, while the other path moves counter clockwise. Horn gears or notched rotors on the deck create the serpentine path. Half the carriers travel in the first path around the braiding point following one serpentine path created by the horn gears while the other half of the carriers travel in the second path, in the opposite direction around the braiding point. As the two sets of carriers travel in opposite directions around the braiding point, each set crosses the path of the other and the strands leaving the filament bobbins are interwoven as they converge to the braiding point. The speed of these machines is limited by the inertia of the carriers and/or changes in tension on the filaments resulting from the continuously changing radial movement towards and away from the point of braid formation.
These types of braiding machines, however, are generally limited to production of braids using lower filament count and/or generally large filaments. Typical braid structures of small filaments are 72, 96 and 144 in a one-over, one-under braid pattern. These same machines, generally of the maypole variety with horn gears and carriers, may also be used to produce 144, 192 or 288 braids of two-over, two-under construction. Very large “Megabraiders” have been manufactured with up to 800 carriers that will produce high filament count braids. See http://www.braider.com/About/Megabraiders.aspx. These Megabraiders, however, are generally used for large structures and are not suitable for most medical applications that require construction with fine wires that have low tensile strength.
The internal cam rotary type braiding machine, known as the Wardwell Rapid Braider, uses a high-speed braiding process. This type of machine uses a plurality of lower carrier members and a plurality of upper carrier members, which travel past each other in continuous circular paths centered about the braid axis, going in opposite directions. As the upper and lower carriers travel past each other in opposite directions, strands from bobbins on the lower carriers are intertwined with strands from bobbins on the upper carriers. Deflectors are used to lift strands of the lower carriers up and over strands from the upper carriers, so that only the strands of the lower carriers are alternately passed over and under strands of the upper carriers to create the interwoven pattern. The Wardwell Braider, however, becomes unreliable when trying to braid strands or filaments of material, particularly very fine wire materials, having extremely small diameters. The rotary technique used therein produces so much tension on the very small diameter materials, particularly at one stage of the braiding process, that such extremely fine filaments tend to break, requiring that the machine be stopped.
Thus, it would be desirable to provide a braiding machine and process capable of manufacturing high wire count tubular braids of small diameter filaments without breakage.